The present invention relates to a device for diffusing in the soil volatile treatment products, in particular multi-component products.
Phytosanitary treatment products in the form of granules are known that are dispersed in the soil by ploughing in, or burial, and which, by gradually reacting in the presence of the moisture of the soil, exert their action upon the organisms to be eliminated.
Such products are generally aggressive, but it is relatively easy to handle them in solid form.
In the case of other products, or so-called products to be applied by fumigation, it is necessary to turn up the soil, discharge a stream of gas at the bottom of a furrow and cover the furrow with earth immediately afterwards. Such an application entails real difficulties.
For this kind of application, there is provided a frame mounted on the three-point linkage of a tractor. This chassis is provided with coulters designed to inject the treatment gases into the soil. However, these coulters do not penetrate the soil deeply and they have to be close to one another to ensure correct treatment. As a result, considerable clogging with roots occurs and the user has to raise the linkage in order to clear the coulters of the accumulated vegetation, which can give rise to treatment gas fumes and is not satisfactory. If the user takes the time to carry out the manoeuvre correctly, that is to say if he waits for the gas to cease flowing, he wastes considerable time.
In addition, penetration depth is irregular, and injection at the correct depth is thus not always possible, leading to application inconsistent with specifications.
The injection systems are also known to use compressed air pumps which work at constant pressure and delivery rates. These systems are not, however, suitable as they produce dosages that are not proportional, which leads to dosages that are either excessive or insufficient. Moreover, they consume unnecessary quantities of products that are relatively expensive since they are sophisticated and highly technical.
Existing diffusion means further have the drawback of being corroded by products that are particularly aggressive. It is thus conceivable that a pump may be provided that affords good resistance to one of the treatment products but generally poor resistance to others. Changing over pumps according to the products used cannot, however, be contemplated. Thus, users are obliged to replace and service the pumps very frequently, which increases treatment costs accordingly.
New products resulting from in-depth research that are commercially available offer quite clear advantages, in particular as to treatment efficiency. Mention can be made, in particular, of the one marketed by the Calliope company under the name of xe2x80x9cEnzonexe2x80x9d.
On the other hand, these products are more difficult to handle. Indeed, while the solvent-dispersant required is very simple, since it is water, the active principle, on the other hand, is hydro-reactive and generates a gaseous product immediately after being brought into contact with water. It is thus not possible to prepare the mixture in advance as a pressure vessel would be needed. In addition, the efficiency of such products is often maximal at the time of reaction and decreases in time. The products need to be injected simultaneously in situ, as the treatment progresses, that is to say into the soil.
The present invention provides a device which permits the diffusion of such products including at least two inter-reactive compounds, which precludes any risk of pressurising the on-board storage tank, which prevents losses and approximate dosages by operating in DPA mode, i.e. at a delivery rate proportional to advance, while, at the same time, enabling the volume diffused per unit of surface to be adjusted very simply, which is highly reliable thanks to the combination of mechanical means which are themselves simple, hence reliable, which can use different products with the same pump, which diffuses the gas stream continuously and at the right depth in the soil, which prevents any clogging and the need to raise the frame, and which is designed to be connected also to the three-point linkage of a tractor like the majority of known agricultural machines.
For this purpose, the device for diffusing volatile treatment products in the soil, in particular at least two inter-reactive products for application by fumigation, which is the object of the present invention, includes a frame, connecting means for connecting the frame to the three-point linkage of a tractor, and means for storing the products, and is characterised in that it includes, installed on the frame, means for pumping the products contained in the storage means, supply circuits in which are disposed the pumping means and which connect the storage means to a manifold having at least two inputs and one output, and diffusion means borne by at least one coulter and connected to the output of the manifold to diffuse in the soil, when the coulter is introduced into the latter, a gas stream resulting from the reaction of the inter-reactive products.
Preferably, the diffusion means include a common tube which is disposed downstream of the coulter, parallel to the edge and over its entire height, and the open lower end of which emerges in the area of the heel of said coulter.
As to the coulter, it preferably includes subsoil ploughing wings at its lower end.
According to one particular feature of the invention, the pumping means include one pump per product and are preferably constituted by peristaltic pumps.
The diffusion device according to the invention further includes means for travelling over the soil and means for actuating the peristaltic pumps when the travelling means are rotated, so that the delivery rate of said pumps is proportional to advance.
Preferably, the travelling means include at least one free running wheel rotatably mounted on the end of a rocker arm capable of pivoting on the frame about a pin, a return member being interposed between the frame and the rocker arm to press the free running wheel against the soil.
Preferably also, the means for driving the peristaltic pumps include a chain interposed between a driving plate rotationally integral with the wheel and a driven plate rotationally integral with a shaft designed to drive the pumps, as well as a chain adjuster to compensate for variations in the length of the chain.
Furthermore, the diffusion device according to the invention can advantageously include a roller located rearwards of the coulter and designed to compact the soil and set the furrow produced by the coulter as the tractor moves.
In the form of embodiment that has just been described, there are thus provided two supply circuits connecting two treatment product-storing means to a common manifold to which the diffusing means are connected, these circuits being completely independent of one another and ensuring a flow rate proportional to the advance of the tractor.
According to an alternative embodiment, the diffusion device according to the invention includes a radar for detecting the speed of advance of the tractor; a hydraulic circuit including an oil tank, at least one pump, two hydraulic motors for driving the pumping means and two proportional valves to supply the hydraulic motors; sensors associated with the pumping means for detecting the delivery rates of the latter; and a computer to which the radar and the delivery rate sensors are coupled, and which is designed to drive the proportional valves according to the signals received from said radar and said sensors in order to determine the quantities of inter-reactive products to be delivered by the pumping means to the diffusion means.
Thanks to this combination of arrangements, it is possible to diffuse in the soil quantities of treatment products that are far more precise.
To facilitate the user""s task, the computer is preferably installed on the tractor.
Thus, the user, by applying simple keystrokes to the keyboard, can change the delivery rates of the pumping means according to the treatment to be carried out.
The diffusion device according to the invention can further advantageously include a switch to interrupt the operation of the pumping means when the coulter is withdrawn from the soil and to command the operation of said pumping means when the coulter penetrates the soil.
Thus, when the tractor reaches one of the ends of a field to be treated and the user withdraws the coulter from the soil by raising the diffusion device by means of the three-point linkage, the treatment products cease to be directed towards the diffusion means, which prevents the gas stream from being emitted into the atmosphere.
Of course, the switch will once more cause the pumping means to operate as soon as the user lowers the diffusion device to introduce the coulter into the soil.